Application of CWPO to the treatment of pharmaceutical emerging pollutants in different water matrices with a ferromagnetic catalyst

Reusable adsorbent of magnetite in mesoporous carbon for antibiotic removal

This study aims to evaluate the feasibility of an innovative reusable adsorbent through adsorption-degradation sequence for antibiotic removal from water. The magnetite/mesoporous carbon adsorbent was prepared using a two-step method of (i) in situ impregnation of magnetite precursor during resorcinol formaldehyde polymerization and (ii) pyrolysis at elevated temperature (800 °C). XRD spectra confirmed that magnetite (Fe3O4) was the only iron oxide species present in the adsorbent, and thermogravimetric analysis revealed that its content was 10 wt%. Nitrogen sorption analysis showed that Fe3O4/carbon features a high fraction of mesopores (> 80 vol.%) and a remarkable specific surface area value (246 m2 g-1), outstanding properties for water treatment. The performance of the adsorbent was examined in the uptake of three relevant antibiotics. The maximum adsorption uptakes were ca. 76 mg g-1, ca. 70 mg g-1, and ca. 44 mg g-1 for metronidazole, sulfamethoxazole, and ciprofloxacin, respectively. All adsorption curves were successfully fitted with Langmuir equilibrium model. The regeneration of adsorbent was carried out using Fenton oxidation under ambient conditions. After three consecutive runs of adsorption-regeneration, Fe3O4/carbon maintained its performance almost unchanged (up to 95% of its adsorption capacity), which highlights the high reusability of the adsorbent.

Study on the Performance Test of Fe-Ce-Al/MMT Catalysts with Different Fe/Ce Molar Ratios for Coking Wastewater Treatment

It is very important to choose a suitable method and catalyst to treat coking wastewater. In this study, Fe-Ce-Al/MMT catalysts with different Fe/Ce molar ratios were prepared, characterized by XRD, SEM, and N2 adsorption/desorption, and treated with coking wastewater. The results showed that the optimal Fe-Ce-Al/MMT catalyst with a molar ratio of Fe/Ce of 7/3 has larger interlayer spacing, specific surface area, and pore volume. Based on the composition analysis of real coking wastewater and the study of phenol simulated wastewater, the response surface test of the best catalyst for real coking wastewater was carried out, and the results are as follows: initial pH 3.46, H2O2 dosage 19.02 mL/L, Fe2+ dosage 5475.39 mL/L, reaction temperature 60 °C, and reaction time 248.14 min. Under these conditions, the COD removal rate was 86.23%.

Heterogeneous Fenton system driven by iron-loaded sludge biochar for sulfamethoxazole-containing wastewater treatment

In this study, the treatment performance of a heterogeneous Fenton system (Fe-BC + H₂O₂) driven by iron-loaded sludge biochar (Fe-BC) on wastewater containing sulfamethoxazole (SMX) was investigated using the CODcr removal efficiency (φ) as an indicator. The batch experimental results showed that the optimal operating conditions were as follow: initial pH 3, H₂O₂ concentration 20 mmol L^-1, Fe-BC dose 1.2 g L^-1, temperature 298 K. The corresponding φ was as high as 83.43%. The removal of CODcr was better described by BMG model and revised BMG (BMGL) model. According to the BMGL model, the φ_max could be 98.37% (298 K). Moreover, the removal of CODcr was a diffusion-controlled process, while liquid film diffusion and intraparticle diffusion together determined its removal rate. The removal of CODcr should be a synergistic effect of adsorption and Fenton oxidation (real heterogeneous Fenton and homogeneous Fenton) and other pathways. Their contributions were 42.79%, 54.01% and 3.20%, respectively. For homogeneous Fenton, there seemed to be two simultaneous SMX degradation pathways: SMX→4-(pyrrolidine-11-sulfonyl)-aniline→N-(4-aminobenzenesulfonyl) acetamide/4-amino-N-ethyl benzene sulfonamides→4-amino-N-hydroxy benzene sulfonamides; SMX→N-ethyl-3-amino benzene sulfonamides→4-methanesulfonylaniline. In summary, Fe-BC had potential for practical application as a heterogeneous Fenton catalyst.

Critical review of technologies for the on-site treatment of hospital wastewater: From conventional to combined advanced processes

This review aims to assess different technologies for the on-site treatment of hospital wastewater (HWW) to remove pharmaceutical compounds (PhCs) as sustances of emerging concern at a bench, pilot, and full scales from 2014 to 2020. Moreover, a rough characterisation of hospital effluents is presented. The main detected PhCs are antibiotics and psychiatric drugs, with concentrations up to 1.1 mg/L. On the one hand, regarding the presented technologies, membrane bioreactors (MBRs) are a good alternative for treating HWW with PhCs removal values higher than 80% in removing analgesics, anti-inflammatories, cardiovascular drugs, and some antibiotics. Moreover, this system has been scaled up to the pilot plant scale. However, some target compounds are still present in the treated effluent, such as psychiatric and contrast media drugs and recalcitrant antibiotics (erythromycin and sulfamethoxazole). On the other hand, ozonation effectively removes antibiotics found in the HWW (>93%), and some studies are carried out at the pilot plant scale. Even though, some families, such as the X-ray contrast media, are recalcitrant to ozone. Other advanced oxidation processes (AOPs), such as Fenton-like or UV treatments, seem very effective for removing pharmaceuticals, Antibiotic Resistance Bacteria (ARBs) and Antibiotic Resistance Genes (ARGs). However, they are not implanted at pilot plant or full scale as they usually consider extra reactants such as ozone, iron, or UV-light, making the scale-up of the processes a challenging task to treat high-loading wastewater. Thus, several examples of biological wastewater treatment methods combined with AOPs have been proposed as the better strategy to treat HWW with high removal of PhCs (generally over 98%) and ARGs/ARBs (below the detection limit) and lower spending on reactants. However, it still requires further development and optimisation of the integrated processes.

Advanced bio-oxidation of fungal mixed cultures immobilized on rotating biological contactors for the removal of pharmaceutical micropollutants in a real hospital wastewater

Hospital wastewater represents an important source of pharmaceutical active compounds (PhACs) as contaminants of emerging concern for urban wastewater treatment plants. This work evaluates a fungal biological treatment of a hospital effluent before discharging in the municipal sewer system. This treatment was performed in rotating biological contactors (RBCs) covered with wooden planks in order to promote the attachment of the fungal biomass. These bioreactors, initially inoculated with Trametes versicolor as white rot fungi, have created biofilms of a diversified population of fungal (wood-decaying fungi belonging to Basidiomycota and Ascomycetes) and bacterial (Beta-proteobacteria, Firmicutes, and Acidobacteria) microorganisms. The mixed fungal/bacterial community achieved a stable performance in terms of carbon, nitrogen, and phosphorous reductions for 75 days of continuous operation. Moreover, a remarkable removal of pharmaceutical micropollutants was accomplished especially for antibiotics (98.4 ± 0.7, 83 ± 8% and 76 ± 10 for azithromycin, metronidazole and sulfamethoxazole, respectively). Previous studies have proven a high efficiency of fungi for the removal of microcontaminants as a result of advanced bio-oxidation processes mediated by oxidizing hydroxyl radicals. This study evidences the development of a stable fungal-bacterial mixed culture over wooden-modified RBCs for in-situ removal of pharmaceutical compounds of hospital wastewater under non-sterile conditions and non-strict temperature control, avoiding periodical fungal inoculation due to destabilization and displacement of fungal cultures by indigenous wastewater bacteria.

Direct 3D printing of zero valent iron@polylactic acid catalyst for tetracycline degradation with magnetically inducing active persulfate

Catalyst stability has become a challenging issue for advanced oxidation processes (AOPs). Herein, we report an alternative method based on 3D printing technology to obtain zero-valent iron polylactic acid prototypes (ZVI@PLA) in a single step and without post etching treatment. ZVI@PLA was used to activate persulfate (PS) for the removal of Tetracycline (TC) in recirculating mode under two different heating methodologies, thermal bath and contactless heating promoted by magnetic induction (MIH). The effect of both heating methodologies was systematically analysed by comparing the kinetic constant of the degradation processes. It was demonstrated that the non-contact heating of ZVI by MIH reactivates the surface of the catalyst, renewing the surface iron content exposed to the pollutant solution, which makes the ZVI@PLA catalyst reusable up to 10 cycles with no efficiency reduction. In contrast, by using a conventional thermal bath, the kinetic constant gradually decreases over the 10 cycles, because of the superficial iron consumption, being the kinetic constant 5 times lower in the 10th run compared to MIH experiment. X-ray diffraction and Mössbauer spectroscopy confirmed the presence of metallic iron embedded in the ZVI@PLA prototype, whose crystalline structure remained unchanged for 10th cycles of MIH. Moreover, it was proven that with no contact heating technology at low magnetic fields (12.2 mT), the solution temperature does not increase, but only the surface of the catalyst does. Under these superficial heated conditions, kinetic rate is increased up to 0.016 min^-1 compared to the value of 0.0086 min^-1 obtained for conventional heating at 20 °C. This increase is explained not only by PS activation by iron leaching but also by the contribution of ZVI in the heterogeneous activation of persulfate.

Recent advances in magnetic carbon nanotubes: synthesis, challenges and highlighted applications

Magnetic carbon nanotubes (MCNTs), consisting of carbon nanotubes (CNTs) and magnetic nanoparticles (MNPs), have enormous exploration and application potentials due to their superior physical and chemical properties, such as unique magnetism and high enrichment performance. This review concentrates on the rapid advances in the synthesis and application of magnetic carbon nanotubes. Great progress has been made in the preparation of MCNTs by developing methods including chemical vapor deposition, pyrolysis procedure, sol-gel process, template-based synthesis, filling process and hydrothermal/solvothermal method. Various applications of MCNTs as a mediator of the adsorbent in magnetic solid-phase extraction, sensors, antibacterial agents, and imaging system contrast agents, and in drug delivery and catalysis are discussed. In order to overcome the drawbacks of MCNTs, such as sidewall damage, lack of convincing quantitative characterization methods, toxicity and environmental impact, and deficiency of extraction performance, researchers proposed some solutions in recent years. We systematically review the latest advances in MCNTs and discuss the direction of future development.

Degradation of ranitidine and changes in N-nitrosodimethylamine formation potential by advanced oxidation processes: Role of oxidant speciation and water matrix

This study investigated the effects of thirteen (photo/electro) chemical oxidation processes on the formation potential (FP) of N-nitrosodimethylamine (NDMA) during the chloramination of ranitidine in reverse osmosis (RO) permeate and brine. The NDMA-FP varied significantly depending on the pretreatment process, initial pH, and water matrix types. At higher initial pH values (> 7.0), most pretreatments did not reduce the NDMA-FP, presumably because few radical species and more chloramine-reactive byproducts were generated. At pH < 7.0, however, electrochemical oxidation assisted by chloride and Fe²⁺/H₂O₂, catalytic wet peroxide oxidation and peroxydisulfate-induced pretreatments removed up to 85% of NDMA-FP in the RO brine. Ultraviolet (UV) irradiation or prechlorination alone did not reduce the NDMA-FP effectively, but combined UV/chlorine treatment effectively reduced the NDMA-FP. In contrast, after UV irradiation (2.1 mW cm^-2 for 0.5 h) in the presence of H₂O₂ and chloramine, NDMA formation increased substantially (up to 26%) during the post-chloramination of the RO permeate. Mass spectrometric analysis and structural elucidation of the oxidation byproducts indicated that compared with the reactive nitrogen species generated by UV/NH₂Cl, sulfate radicals and (photo/electro)chemically generated reactive chlorine species were more promising for minimizing NDMA-FP. Unlike, the hemolytic •OH driven by UV/H₂O₂, the •OH from Fe(IV)-assisted pretreatments showed a significant synergistic effect on NDMA-FP reduction. Overall, the results suggest the need for a careful assessment of the type of radical species to be used for treating an RO water system containing amine-functionalized compounds.

Pyrolyzed carbon derived from red soil as an efficient catalyst for cephalexin removal

Red soil, a typical soil type in southern China, has been deemed infertile or nutrient-deficient. In this study, red soil was firstly utilized as a substrate for preparing catalysts, which were then successfully applied to the catalytic wet peroxide oxidation (CWPO) of cephalexin. The highest cephalexin removal was 95.23% and TOC removal was 60.58%, with the catalyst pyrolyzed at 500 °C (RC500). The high iron content and proportion of Fe(II) on the surface of RC500 was responsible for the decomposition of H₂O₂ into· OH. Moreover, the porous structure and existence of other minerals (such as SiO₂ and Al₂O₃) in the catalyst were also significant for enhancing the catalytic activity of RC500. Afterwards, the influencing parameters, including temperature, pH, the dose of H₂O₂, and catalyst, were examined for cephalexin degradation. It was noteworthy that RC500 was efficient in treating hospital wastewater when using a self-design pilot device. A density functional theory analysis of cephalexin was conducted to establish the possible position attacked by ·OH, and the possibly ruptured one. Meanwhile, the intermediates generated during CWPO were identified. Finally, a reliable degradation pathway of cephalexin was proposed on the basis of the results.

Magnetite-Based Catalyst in the Catalytic Wet Peroxide Oxidation for Different Aqueous Matrices Spiked with Naproxen–Diclofenac Mixture

Magnetite supported on multiwalled carbon nanotubes catalysts were synthesized by co-precipitation and hydrothermal treatment. The magnetic catalysts were characterized by X-ray diffraction, Fourier-transform infrared spectrometry, thermogravimetric analysis and N2 physisorption. The catalysts were then tested for their ability to remove diclofenac (DCF) and naproxen (NAP) from an aqueous solution at different conditions (pH, temperature, and hydrogen peroxide) to determine the optimum conditions for chemical oxidation. The optimization of the process parameters was conducted using response surface methodology (RSM) coupled with Box–Behnken design (BBD). By RSM–BBD methodology, the optimal parameters (1.75 mM H2O2 dosage, 70 °C and pH 6.5) were determined, and the removal percentages of NAP and DCF were 19 and 54%, respectively. The NAP–DCF degradation by catalytic wet peroxide oxidation (CWPO) was caused by •OH radicals. In CWPO of mixed drug solutions, DCF and NAP showed competitive oxidation. Hydrophobic interactions played an important role during the CWPO process. On the other hand, the magnetic catalyst reduced its activity after the second cycle of reuse. In addition, proof of concept and disinfection tests performed at the operating conditions showed results following the complexity of the water matrices. In this sense, the magnetic catalyst in CWPO has adequate potential to treat water contaminated with NAP–DCF mixtures.

Post-treatment of real municipal wastewater effluents by means of granular activated carbon (GAC) based catalytic processes: A focus on abatement of pharmaceutically active compounds

Pharmaceutically active compounds (PhACs) widely present in urban wastewater effluents pose a threat to ecosystems in the receiving aquatic environment. In this work, efficiency of granular activated carbon (GAC) - based catalytic processes, namely catalytic wet peroxide oxidation (CWPO), peroxymonosulfate oxidation (PMS/GAC) and peroxydisulfate oxidation (PDS/GAC) at ambient temperature and pressure were studied for removal of 22 PhACs (ng L^-1 level) that were present in secondary effluents of real urban wastewater. Concentrations of PhACs were measured using Ultra Performance Liquid Chromatography - Triple Quadrupole Mass Spectrometry (UPLC-QqQ-MS/MS). Catalytic experiments were conducted in discontinuous mode using up-flow fixed bed reactors with granular activated carbon (GAC) as a catalyst. The catalyst was characterized by means of N₂ adsorption-desorption isotherm, mercury intrusion porosimetry (MIP), elemental analysis, X-ray fluorescence spectroscopy (WDXRF), X-ray diffraction (XRD), thermal gravimetry and differential temperature analyses coupled mass spectrometry (TGA-DTA-MS). Results indicate that the highest efficiency in terms of TOC removal was achieved during CWPO performed at optimal operational conditions (stoichiometric dose of H₂O₂; TOC removal ~ 82%) followed by PMS/GAC (initial PMS concentration 100 mg L^-1; TOC removal ~73.7%) and PDS/GAC (initial PDS concentration 100 mg L^-1; TOC removal ~ 67.9%) after 5 min of contact time. Full consumption of oxidants was observed in all cases for CWPO and PDS/GAC at contact times of 2.5 min, while for PMS/GAC it was 1.5 min. In general, for 18 out of 22 target PhACs, very high removal efficiencies (> 92%) were achieved in all tested processes (including adsorption) performed at optimal operational conditions during 5 min of contact time. However, moderate (40 - 70%) and poor (< 40%) removal efficiencies were achieved for salicylic acid, ofloxacin, norfloxacin and ciprofloxacin, which can be possibly attributed to insufficient contact time. Despite high efficiency of all studied processes for PhACs elimination from urban wastewater effluent, CWPO seems to be more promising for continuous operation.

New insights on the removal of diclofenac and ibuprofen by CWPO using a magnetite-based catalyst in an up-flow fixed-bed reactor

This research has been focused on the removal of two anti-inflammatory drugs, diclofenac (DCF) and ibuprofen (IBU), by a continuous catalytic wet peroxide oxidation (CWPO) process using a lab-synthesized nanomagnetic catalyst (Fe₃O₄/MWCNTs). The central composite rotatable design (CCRD) method was used to study the effect of DCF and IBU concentration (expressed as theoretical oxygen demand (ThOD) between 0 and 52.5 mg L^-1) and of the feed stream pH (from 3 to 7) on the removal of total organic carbon (TOC) and the concentration of aromatic compounds (Arm) and total phenolic compounds (TP) by CWPO. It could be observed that DCF was preferably removed from the DCF-IBU aqueous mixture at pH values ranging from 3 to 5. In addition, feed stream pH had a significant effect on the pollutants removal, as well as on TOC, TP and aromatic compounds removal, observing an increasing in the pollutants degradation when feed stream pH decreased from 7 to 3. Quadratic models predicted for response variable, such as TOC, TP and aromatic compounds removal, and their maximum model-predicted removal values were of 90.0, 80.2 and 90.0%, respectively. Finally, as a proof of concept, three environmentally-relevant aqueous matrices, spiked with DCF-IBU mixture, were treated. In this case, relatively high TOC degradation values were found after 20 h reaction time (ca. 57.7, 73.9 and 54.5% in surface water, WWTP effluent and hospital wastewater, respectively). This work deals the first study about DCF-IBU removal in aqueous solution by CWPO, as well as a continuous study using real wastewater that allow to extend the experimental results to a real scenario.

Targeted eco-pharmacovigilance as an optimized management strategy for adverse effects of pharmaceuticals in the environment

From a perspective of drug administration, eco-pharmacovigilance (EPV) has been proposed as a new approach to prevent the environmental risks posed by pharmaceutical emerging contaminants. However, it is impracticable to practice unitary and rigor EPV process for all the pharmaceutical substances with complex and diversified chemical, biological or toxicological properties. We proposed the "targeted EPV" that is the science and activities associated with the targeted detection, evaluation, understanding, and prevention of adverse effects of high-priority hazardous pharmaceuticals in the environment, especially focusing on the control of main anthropogenic sources of pharmaceutical emission among key stakeholders in high-risk areas could be used as an optimized management strategy for pharmaceutical pollution. "Targeted EPV" implementation should focus on the targeted monitoring of the occurrence of high-priority pharmaceuticals in environmental samples, the targeted reporting of over-standard discharge, the targeted management for main emission sources, the targeted legislation and researches on high-priority pharmaceutical pollutants, as well as the targeted educational strategies for specific key populations.

Removal of emerging pollutants in aqueous phase by heterogeneous Fenton and photo-Fenton with Fe2O3-TiO2-clay heterostructures

Fe₂O₃-TiO₂-clay heterostructures have been prepared using an organo-bentonite as support, which organophilic character favored the fixation of TiO₂. Furthermore, Fe₂O₃ was successfully anchored by wet impregnation. The resulting materials are characterized by a disordered layered structure and a mesoporous texture. The heterostructures were employed as catalysts for the removal of two pharmaceuticals, acetaminophen (ACE) and antipyrine (ANT), by heterogeneous Fenton and photo-Fenton processes. ACE removal under different operation conditions was studied in detail to establish structure-performance relationships, being the TiO₂ formation and the developed texture the main factors controlling the activity. ANT showed a higher refractory behavior in oxidation by Fenton. Among the technologies studied, heterogeneous photo-Fenton achieved the best catalytic performance and higher kinetic rate and mineralization degree. Iron leaching was very low, lower than 5% of the initial iron load in all cases. This work demonstrates the potential application of these heterostructures for the removal of emerging pollutants of different nature.

Efficient degradation of sulfamethoxazole by catalytic wet peroxide oxidation with sludge-derived carbon as catalysts

Sulfamethoxazole (SMX) is a commonly used antibiotic for both human and animals. The frequent detection of SMX in natural water bodies and sediment has become an issue of great environmental concern due to its potential risk to induce antibiotic resistance in pathogenic bacteria. In the present work, the catalytic wet peroxide oxidation (CWPO) was investigated to remove SMX with sludge-derived carbon (SC) as a cheap alternative catalyst. Different acids were used to modify SC. It was found that SC modified with sulphuric acid (SC-H₂SO₄) demonstrated the best catalytic activity. The removal efficiency of SMX and TOC was 97.7% and 65.7%, respectively, after 260 min, at pH 5 with a dosage of 220 mg/L H₂O₂. The effects of temperature, initial pH and H₂O₂ dosage were also investigated. The study demonstrated that the increase of temperature could significantly improve the degradation of SMX from 10.0% at 20°C to 94.7% at 60°C.

Magnetic Fe3O4/multi-walled carbon nanotubes materials for a highly efficient depletion of diclofenac by catalytic wet peroxideoxidation

The aim of this work is to synthesize a magnetic magnetite/multi-walled carbon nanotube (Fe₃O₄/MWCNT) catalyst by a method combining co-precipitation and hydrothermal treatments for the efficient removal of diclofenac (DCF) by catalytic wet peroxide oxidation (CWPO). The support (MWCNTs) shows a moderate-large surface area and good adsorption capacity, leading to the improvement of the magnetite (Fe₃O₄) dispersion on its surface. The response surface methodology (RSM) was applied in order to find out the effect of the reaction parameters on DCF removal, allowing to establish the optimum operating conditions (T = 60 °C, [H₂O₂]₀ = 2.7 mM, [catalyst] = 1.0 g L^-1). The optimum CWPO experiment showed an outstanding catalytic activity at non-modified pH solution (6.7), obtaining a 95% of DCF removal after 3 h reaction time; this high efficiency can be attributed to the synergistic effect of the iron-based catalyst with the high quantity of ^•OH radicals generated on the surface of the catalyst. In addition, the Fe₃O₄/MWCNT material exhibited good reusability along three consecutive reaction cycles, finding a pollutant removal close to 95% in each cycle of 3 h reaction time. Additionally, a degradation mechanism pathway was proposed for the removal of DCF by CWPO. The versatility of the material was finally demonstrated in the treatment of different environmentally relevant aqueous matrices (a wastewater treatment plant effluent, surface water, and hospital wastewater), obtaining an effective reduction in the ecotoxicity values.

Catalytic Degradation of Textile Wastewater Effluent by Peroxide Oxidation Assisted by UV Light Irradiation

Textile industries produce a complex wastewater which is difficult to be treated. In this work, a catalytic degradation of wastewater effluent composed of sulphur black coloring agent discharged by industry was studied. UV lamp power, peroxide concentration, pH, and iron oxide catalyst were varied to determine the best conditions for oxidative treatment. Kinetic parameters were evaluated based on the reaction model proposed. In the absence of iron oxide catalyst, chemical oxygen demand (COD) and biological oxygen demand (BOD) degradation of up to 80% and 75%, respectively, were observed as resulting from using an H2O2 concentration of 0.61 moles/L, UV lamp power of 30 watts, and pH of 6. When using an iron oxide catalyst combined with UV light irradiation, the degradation rate could be increased significantly, while similar final COD and BOD degradation percentages resulted. It is found that the reaction rate order was shifted from first order to second order when using an H2O2/UV/Fe2O3 system. The results could be an alternative for treating textile industry wastewater, and the parameters obtained can be used for equipment scale-up.

Ultrasound-assisted synthesis of thermosensitive nanovesicle for direct trap and release of analgesic drugs in biofluid and sewage

An environmentally friendly thermosensitive nanovesicle-cloud point microextraction technique has been developed with the assistant of ultrasonic waves to determine analgesic drugs with a broad range of polarity in field water and human urine. Based on thin-film hydration, the conformation of nanovesicles formed by a binary mixing system with the nonionic surfactants was evaluated using regular and cryogenic transmission electron microscopy. The multilayered nano-spherical structure was able to capture polar and nonpolar compounds simultaneously. Analgesic drugs (acetaminophen, salicylic acid, ketoprofen, diclofenac, indomethacin, ibuprofen, and mefenamic acid) were detected by ultra-performance liquid chromatography coupled to photodiode array detection. Under optimal conditions including the type and ratio of surfactants, sonication time and sonication temperature, linear calibration curves were obtained over the range of 50-8000 μg L^-1. The coefficient of determination (R²) ranged from 0.9953 to 0.9995, with detection limits of 10-100 μg L^-1. The relative standard deviations ranged from 3.2% to 12.7% for intraday precision (n = 5) and 2.5% to 14.1% for interday precision (n = 15). The relative recoveries obtained from one industrial wastewater sample and two field water samples ranged from 86.1% to 108.1%. In the human urine analysis, three volunteers ingested 1500 mg of acetaminophen. After 4 h, the concentration of acetaminophen in the urine was found to range from 87.0 to 197.9 mg L^-1.

Solar-Driven Removal of 1,4-Dioxane Using WO3/nγ-Al2O3 Nano-catalyst in Water

Increasing demand for fresh water in extreme drought regions necessitates potable water reuse. However, current membrane-based water reclamation approaches cannot effectively remove carcinogenic 1,4-dioxane. The current study reports on the solar-driven removal of 1,4-dioxane (50 mg L−1) using a homemade WO3/nγ-Al2O3 nano-catalyst. Characterization methods including scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence (XRF) analyses are used to investigate the surface features of the catalyst. The 1,4-dioxane mineralization performance of this catalyst under various reaction conditions is studied. The effect of the catalyst dosage is tested. The mean oxidation state carbon (MOSC) values of the 1,4-dioxane solution are followed during the reaction. The short chain organic acids after treatment are measured. The results showed that over 75% total organic carbon (TOC) removal was achieved in the presence of 300 mg L−1 of the catalyst with a simulated solar irradiation intensity of 40 mW cm−2. Increasing the dose of the catalyst from 100 to 700 mg L−1 can improve the treatment efficiency to some extent. The TOC reduction curve fits well with an apparent zero-order kinetic model and the corresponding constant rates are within 0.0927 and 0.1059 mg L−1 s−1, respectively. The MOSC values of the 1,4-dioxane solution increase from 1.3 to 3 along the reaction, which is associated with the formation of some short chain acids. The catalyst can be effectively reused 7 times. This work provides an oxidant-free and energy saving approach to achieve efficient removal of 1,4-dioxane and thus shows promising potential for potable reuse applications.

Attitudes and Practice Regarding Disposal for Unwanted Medications among Young Adults and Elderly People in China from an Ecopharmacovigilance Perspective

Due to the expensive cost and uncertain effectiveness of environmental management options in eliminating pharmaceutical residues, recently, decreasing the emission of pharmaceutical pollutants from a drug administration perspective has been considered a hot area of research. As a kind of drug administration for the environment, ecopharmacovigilance (EPV) emphasizes the source control of pharmaceutical pollutants. Disposal of unwanted medicines has been considered as the easiest target for source control of pharmaceutical contamination. Here, we focused on public attitudes and practice regarding disposal of unwanted medicines from the EPV perspective among 365 Chinese university young adults and 206 elderly retirement home residents. The results showed that the majority of respondents had positive attitudes, but exhibited inadequate awareness and poor practice. In addition, the young-adult respondents were found to pay more attention to the environmental problems posed by pharmaceutical residues, and be more supportive of the EPV intervention predominantly performed by pharmaceutical industries and pharmacists. Therefore, it is urgent to establish the standard medicine disposal protocols and educate the general public on the best way for medication disposal under the principle of EPV in China, and efforts on environmentally-preferred drug disposal under EPV should target for the specific demographics.

Application of Catalytic Wet Peroxide Oxidation for Industrial and Urban Wastewater Treatment: A Review

Catalytic wet peroxide oxidation (CWPO) is emerging as an advanced oxidation process (AOP) of significant promise, which is mainly due to its efficiency for the decomposition of recalcitrant organic compounds in industrial and urban wastewaters and relatively low operating costs. In current study, we have systemised and critically discussed the feasibility of CWPO for industrial and urban wastewater treatment. More specifically, types of catalysts the effect of pH, temperature, and hydrogen peroxide concentrations on the efficiency of CWPO were taken into consideration. The operating and maintenance costs of CWPO applied to wastewater treatment and toxicity assessment were also discussed. Knowledge gaps were identified and summarised. The main conclusions of this work are: (i) catalyst leaching and deactivation is one of the main problematic issues; (ii) majority of studies were performed in semi-batch and batch reactors, while continuous fixed bed reactors were not extensively studied for treatment of real wastewaters; (iii) toxicity of wastewaters treated by CWPO is of key importance for possible application, however it was not studied thoroughly; and, (iv) CWPO can be regarded as economically viable for wastewater treatment, especially when conducted at ambient temperature and natural pH of wastewater.

Fast degradation of diclofenac by catalytic hydrodechlorination

Aqueous-phase catalytic hydrodechlorination (HDC) has been scarcely explored in the literature for the removal of chlorinated micropollutants. The aim of this work is to prove the feasibility of this technology for the fast and environmentally-friendly degradation of such kind of compounds. Diclofenac (DCF), a highly consumed anti-inflammatory drug, has been selected as the target pollutant given its toxicity and low biodegradability. The commercial Pd/Al₂O₃ (1% wt.) catalyst has been used due to its prominent role on this field. Complete degradation of DCF was achieved in a short reaction time (20 min) under ambient conditions (25 °C, 1 atm) at [DCF]₀ = 68 μM; [Pd/Al₂O₃]₀ = 0.5 g L^-1 and H₂ flow rate of 50 N mL min^-1. Remarkably, the chlorinated intermediate (2-(2-chloroanilino)-phenylacetate (Cl-APA)) generated along reaction was completely removed at the same time, being the chlorine-free compound 2-anilinophenylacetate (APA) the only final product. A reaction scheme based on this consecutive pathway and a pseudo-first-order kinetic model have been proposed. An apparent activation energy of 43 kJ mol^-1 was obtained, a comparable value to those previously reported for conventional organochlorinated pollutants. Remarkably, the catalyst exhibited a reasonable stability upon three successive uses, achieving the complete degradation of the drug and obtaining APA as the final product in 30 min. The evolution of ecotoxicity was intimately related to the disappearance of the chlorinated organic compounds and thus, the final HDC effluents were non-toxic. The versatility of the system was finally demonstrated in different environmentally-relevant matrices (wastewater treatment plant effluent and surface water).

Wet peroxidation of resorcinol catalyzed by copper impregnated granular activated carbon

The present article reports the treatment of resorcinol using a catalytic wet peroxidation (CWPO) process in the presence of copper impregnated granular activated carbon (Cu/GAC) with a bench-scale batch reactor. The typical physico-chemical properties of synthesized catalyst were characterized with different equipment and methods. 90% resorcinol removal and 81% of TOC removal was achieved at optimum conditions (pH = 6, the stoichiometric ratio of H₂O₂/resorcinol = 1.2, catalyst dose = 0.5 g/L, initial concentration of resorcinol = 100 mg/L, temperature = 70 °C and time t = 4 h). Fourier-transform infrared spectroscopy (FTIR) measurements revealed that GAC posses various conjugated hydrocarbon groups including aromatic hydrocarbons, carboxylic groups, carboxyl and carbonate. Cu/GAC catalyst has a surface smoother than that of pristine GAC. At neutral or natural pH (∼6.4) of resorcinol, CWPO of resorcinol is favorable by Cu/GAC catalyst. Catalyst stability study revealed that Cu/GAC sustain its catalytic reactivity to over 76% in the five cycles without any regeneration. The thermogravimetric analysis confirmed that 350 °C temperature found to be optimum for calcination of Cu/GAC without any major losses. The mineralization mechanism was proposed based on intermediates identified during CWPO reaction.

Metal Organic Framework with Coordinatively Unsaturated Sites as Efficient Fenton-like Catalyst for Enhanced Degradation of Sulfamethazine

A novel Fenton-like catalyst, metal organic framework MIL-100(Fe) with Fe^II/Fe^III mixed-valence coordinatively unsaturated iron center (CUS-MIL-100(Fe)), was synthesized, characterized, and used for the degradation of sulfamethazine (SMT). The catalytic performance of CUS-MIL-100(Fe) was investigated on the basis of various parameters, including initial pH, H₂O₂ concentration, catalyst dosage, and initial SMT concentration. The results showed that CUS-MIL-100(Fe) could effectively degrade SMT, with almost 100% removal efficiency within 180 min (52.4% mineralization efficiency), under the reaction conditions of pH 4.0, 20 mg L^-1 SMT, 6 mM H₂O₂, and 0.5 g L^-1 catalyst. Moreover, CUS-MIL-100(Fe) displayed a higher catalytic activity than that of MIL-100(Fe) for SMT degradation. Combined with the physical-chemical characterization, the enhanced catalytic activity can be ascribed to the incorporation of Fe^II and Fe^III CUSs (coordinatively unsaturated metal sites), the large specific surface area, as well as the formation of mesopores. Furthermore, CUS-MIL-100(Fe) exhibited a good stability and reusability. The possible catalytic mechanism of CUS-MIL-100(Fe) was tentatively proposed.

Synthesis and application of pillared clay heterogeneous catalysts for wastewater treatment: a review

The use of pillared interlayered clays (PILCs) as heterogenous catalysts in wastewater treatment technologies, particularly advanced oxidation processes (AOPs), is gaining popularity for the treatment of refractory wastewater effluents. The recent literature involving these solid materials is reviewed, with more focus on studies that aim at reducing the synthesis costs and escalating the synthesis process to industrial scale. Their role as active solid materials in the AOPs such as photocatalysis, catalytic wet peroxide oxidation (CWPO), the Fenton process and catalytic wet air oxidation (CWAO) of refractory organic compounds in polluted aqueous streams is also reviewed. These processes are evaluated to evidence their main direction for future research, particularly with reference to possible industrial use of these technologies to treat refractory organic wastewater using pillared clay-based catalysts. The pillared clay catalysts demonstrate good application prospects for the removal of refractory wastewater effluents using AOP technology. The reviewed studies suggest that the photocatalytic process is useful in low concentrations of these compounds, while CWPO, the Fenton process and CWAO are recommended for higher concentrations. However, catalyst development to reduce the severity of oxidation reaction conditions, with focus on the low cost, catalyst stability, reusability and environmental friendliness are the key aspects to be addressed by future research work.